Human and mammalian health is certainly impacted by the spread of microbial entities at home, school, work and in the environment generally. Despite medical advances in infectious disease prevention and treatment, viruses and bacteria continue to cause a variety of sicknesses and ailments, prompting high absenteeism in schools and places of employment. In the wake of widespread food poisoning and the like, the public has become even further concerned with sanitization, both of person and property. Additionally, deadly antibiotic resistant bacteria like MRSA, formerly a nosocomial infection, is now primarily community acquired. Indeed, the World Health Organization continues to monitor avian flu out of concern for the potential of a serious global pandemic. A principal route for the spread of such infections is contact, either with an infected person (a handshake) or a contaminated object (a doorknob). Consequently, those of skill in the art have focused their research endeavors on the identification and deployment of more efficacious disinfectant and antiseptic compositions, and specifically those that provide both immediate and residual kill of microbes.
Antimicrobial compositions that exhibit rapid and residual kill of numerous bacteria and viruses have been disclosed in U.S. Patent Publication Nos. 2009/0035339, 2005/0271711, 2005/0260243, 2004/0001797, 2003/0235550, and in issued U.S. Pat. No. 7,569,530. Each of these disclosures is incorporated by reference herein. The compositions disclosed in these publications incorporate an organic acid or organic acid mixture and selected short-chain anionic surfactants. These compositions are adapted for direct application to human skin, without causing dryness or irritation. Moreover, they are designed for use with or without a water wash, and provide both immediate and residual effectiveness in either instance against a variety of viruses and bacteria.
A preferred family of anionic surfactants for these compositions are the alkyl glyceryl sulfonates, or Cn-AGS. They have been proven to be highly antimicrobial, yet are among the mildest of all anionic surfactants for human skin. One sodium alkyl glyceryl sulfonate is commercially available from the Proctor and Gamble Corporation, AGS-1214, CAS 68081-95-8. This anionic surfactant contains carbon chain lengths from C10 to C16, but is primarily C12-14.
The general synthesis process for commercial AGS is well established. Examples of the synthesis can be found in U.S. Pat. Nos. 2,989,547 and 3,024,273. The synthesis involves a condensation reaction of a fatty alcohol with epichlorohydrin to afford an ether chlorohydrin which is then ring closed to the epoxide to produce an alkyl glyceryl epoxide (AGE). The epoxide is then treated with a mixture of sodium bisulfite and/or sodium sulfite in a sulfonation reaction to afford AGS.
Although this general process is commercially established, it has significant deficiencies when the resulting surfactant is contemplated as a drug substance for topical antimicrobials. Conventionally, a “heel” of AGS from a previous batch must be added to initiate the reaction and insure a uniform solution, which lowers the yield and creates a potential contamination problem. Additionally, the epoxidation reaction results in variable amounts of ether chlorohydrin monomer, dimer, and trimer. A typical monomer proportion is only 72-76%. These ratios carry over through sulfonation into AGS monomer, dimer, and trimer. Although U.S. Pat. No. 3,024,273 teaches that an increased dimer and trimer percentage leads to increased solubility and is preferred, it has been surprisingly discovered that increased monomer content and reduced dimer and trimer percentages provides increased antimicrobial effectiveness.
What is needed for industrial applications of AGS for antimicrobial compositions, is a process for the synthesis of AGS which minimizes dimer and trimer by-products, can be run in standard plant equipment such as stainless steel reactors, has high throughput, and minimizes cross-contamination among production batches.